[sdiy] SSM2164 last time buys

[Oscar Salas]

Hello Neil: 

> This kind of nicely fits in with the recent discussion
> about reverse
> input protection, with the general consensus being
> resettable
> polyfuses and reverse diodes.  Going from Oscar's
> results it looks
> like a 100mA polyfuse would be enough to protect the 2164.
> 
> Hmmm.... at the lower current range the polyfuses can take
> several
> seconds to trip.
>I'd still look into adding a series
> resistor with a
> local decoupling capacitor as  I don't think we yet
> know how long a
> worst-case 2164 can survive on its own without the -ve
> rail. 
 
A question: How does work the decoupling capacitor on there?


> Oscar: if I may ask, could you do the same experiment but
> this time
> with the +Ve rail disappearing?  Does that have the
> same effect?  Or
> is it _only_ the -Ve rail that needs careful monitoring?

 Yes of course. +V disappearing does not affect the chip, I measured current on negative supply when disconnecting positive supply and actually what it does is reduce the current.



--- On Tue, 3/1/11, Neil Johnson <neil.johnson97 at ntlworld.com> wrote:

> From: Neil Johnson <neil.johnson97 at ntlworld.com>
> Subject: Re: [sdiy] SSM2164 last time buys
> To: "Oscar Salas" <osaiber at yahoo.es>
> Cc: "Synth DIY" <synth-diy at dropmix.xs4all.nl>, "Tim Ressel" <madhun2001 at yahoo.com>
> Date: Tuesday, March 1, 2011, 11:21 AM
> Hi Oscar,
> 
> > Yes I have the same question, it would be great the
> solution just with one resistor. If not the other solution
> would be the resettable fuse. Lets see more opinions!
> 
> This kind of nicely fits in with the recent discussion
> about reverse
> input protection, with the general consensus being
> resettable
> polyfuses and reverse diodes.  Going from Oscar's
> results it looks
> like a 100mA polyfuse would be enough to protect the 2164.
> 
> Hmmm.... at the lower current range the polyfuses can take
> several
> seconds to trip.  I'd still look into adding a series
> resistor with a
> local decoupling capacitor as  I don't think we yet
> know how long a
> worst-case 2164 can survive on its own without the -ve
> rail.
> 
> Oscar: if I may ask, could you do the same experiment but
> this time
> with the +Ve rail disappearing?  Does that have the
> same effect?  Or
> is it _only_ the -Ve rail that needs careful monitoring?
> 
> Cheers,
> Neil
> -- 
> http://www.njohnson.co.uk
>